serial_and_usb

代码说明：

说明：  由电脑圈圈的原程序改写，使用串口3，波特率9600连接上EDNCHINa，电脑圈圈的USB开发板可以测试从串口发送到USB接收的数据，这是上位的程序，很有参考价值。下位机程序另发。(By a computer program to rewrite the original circle, use the serial port 3, connected to the 9600 baud rate EDNCHINa, the computer' s USB development board circle can test from the serial port to send data to the USB receiver, which is top of the procedure, a good reference价值. Bit machine under separate procedures.)